An extremely small percentage of women regret starting a medication abortion. This can help them, but it shouldn’t be pushed on everyone.

Since 2015, pro-life legislators in at least 10 states have introduced bills that would require doctors to inform patients who ask for the abortion pill that the pill can be “reversed” if a woman changes her mind. The “reversal” is an experimental procedure developed by a San Diego doctor named George Delgado that until recently was backed by very little research (there was a 2012 case series documenting its effect in seven pregnancies). But this week, the doctor and six co-authors published a new and much larger case series documenting the procedure’s results over the course of several years in hundreds of cases. The paper, which will be sure to inspire a new round of debate on reversal legislation, concludes that reversal is “safe and effective.”

Abortion reversal isn’t quite as outlandish at it sounds. The abortion “pill” is actually two drugs, mifepristone and misoprostol, which women are instructed to take 24 to 48 hours apart. Delgado and his San Diego–based clinic, Culture of Life, maintain a national hotline for women who take the first pill and then regret their decision to do so. Women who call the hotline are connected with a doctor near them willing to perform the “reversal,” which consists of a series of progesterone doses delivered as soon as possible. Because the mifepristone pill essentially blocks progesterone, known as the “pregnancy hormone,” the idea behind reversal is to overwhelm the woman’s system with progesterone before the mifepristone has a chance to take effect.

The new paper documents the results for 547 women who underwent the progesterone therapy in the ideal window of time, less than 72 hours after taking mifepristone. In that group, the overall success rate of the progesterone therapy was 48 percent; 257 women had successful pregnancies that ended in a live birth. (Four women were lost to follow-up after reaching 20 weeks’ gestation, but were included as successes based on their fetuses’ viability at that time.) Other research suggests that 25 percent of pregnancies or less will continue if the woman simply declines to take the misoprostol, which indicates the “reversal” does indeed work in a significant share of cases. The researchers saw even higher success rates when the drug was delivered via intramuscular injection (64 percent) and via a high oral dose (68 percent).

When reversal first arrived on the scene, pro-choice medical experts suggested the procedure likely wouldn’t make a difference. “Doing nothing and waiting to see what happens is just as effective as intervening with a course of progesterone,” the American Congress of Obstetricians and Gynecologists said in a strongly worded anti-reversal statement in 2015. Dr. Daniel Grossman, a leading critic of reversal laws, told me last year that “There’s no evidence that any kind of treatment is better than doing nothing.”

Just because it’s medically possible doesn’t mean that there should be state-mandated promotion of abortion-pillreversal.

Lately, critics have softened their rhetoric. ACOG’s latest statement on reversal makes no mention of its effectiveness, instead emphasizing that the concept was unproven and “unethical,” because of concerns about Delgado’s smaller early case series. This week Grossman conceded in the Washington Post that the regimen “makes some biological sense.”

Just because it’s medically possible, though, doesn’t mean that there should be state-mandated promotion of abortion-pill reversal. Providers emphasize that the goal when administering the abortion pill should be to make sure patients feel fully confident in the decision, rather than telling them they can always undo it later if they change their mind. And the reversal research is still preliminary. As Grossman told me last year, the laws are “essentially kind of encouraging [women] to participate in an unmonitored research experiment.” The new study is an observational case series, not a randomized placebo-controlled trial because, as the paper notes correctly, it would be unethical to give placebos to women desperate to save their pregnancies. The only way to continue to study the procedure is to do more of them. Meanwhile, the case series was published in Issues in Law & Medicine, a pro-life journal with ties to the American Association of Pro-Life Obstetricians and Gynecologists, where Delgado sits on the board. Delgado told the Washington Post that he did not believe his work would be assessed fairly by a mainstream medical publication.

Regardless of whether abortion-pill reversal works, it’s important to note that the percentage of women who regret a medication abortion halfway through is decidedly tiny. Delgado’s hotline received 1,668 calls between June 2012 and June 2016, and 754 of those women ended up proceeding with progesterone. Meanwhile, medication abortions now make up almost half of all abortions in the United States, according to a Reuters analysis in 2016. According to the Centers for Disease Control and Prevention’s latest count, 123,254 women underwent the procedure in 43 states in 2014—a very conservative estimate, since large states including California and Illinois didn’t report their numbers, and the number of women who seek out “DIY abortions” via illegally procured medication aren’t counted either. Even going with these incomplete numbers, the number of women who regret their medication abortion halfway through clocks in at just 0.3 percent, with fewer than half asking for the reversal. In general, despite pro-life rhetoric about widespread trauma and “post-abortion syndrome,” the overwhelming majority of women in the days after an abortion say it was the right decision.

Some women, however, clearly do waver about their decision to end a pregnancy. The circumstances around abortion are often complicated, and the decision itself is a fork in the road between two entirely different lives; it would be more surprising to find that no one ever had second thoughts about their choice. Some even have third thoughts: Of the 754 women Delgado’s survey who pursued progesterone therapy after their hotline call, 57 changed their minds again and completed the abortion.